Top negotiators on a final transportation reauthorization package are up against a tight deadline, with legislative language needing to be posted three legislative days before a House vote and authorization for current projects set to expire this weekend.

House sources indicated an agreement would need to be reached by Wednesday to have enough time for bill-writers to do their work and to satisfy House rules. But Monday, it appeared that talks over the weekend had not bridged the most important points of contention, and both sides began to gird for what they believe will be a difficult end of the week.

Between the transportation bill, an extension of student loan rates and the potential fallout from the Supreme Court’s health care ruling, Republicans and Democrats alike are hoping they can hit their deadlines instead of being stuck with the blame for failure.

“I’m putting my colleagues on notice. Mr. President, the Senate will stay as long as we have to, end of the week if necessary, to complete this substantial workload,” Senate Majority Leader Harry Reid (D-Nev.) said on the floor Monday. “We hope that there will be cooperation not only in this body but also in the House of Representatives.”

But the path to a deal remains unclear, and the top grievances from House Republicans now are not over what’s already in the bipartisan Senate-approved two-year extension but instead over what’s still missing.

A House GOP leadership aide confirmed that talks continued throughout the weekend between Senate Environment and Public Works Chairman Barbara Boxer (D-Calif.) and House Transportation and Infrastructure Chairman John Mica (R-Fla.). The aide said that based on those talks, Speaker John Boehner (R-Ohio) remains hopeful a deal can be cut by Wednesday evening.

But the aide warned that “nothing is agreed to until everything is agreed to,” explaining that part of the problem remains how conferees will balance compromises on the biggest issues, most notably the Keystone XL oil pipeline and changes to the environmental permit process that would expedite and streamline reviews.

House Republicans have made clear in talks with Boxer that “if you don’t want to do Keystone, you’re going to have to give a lot on streamlining, and if you don’t want to do streamlining, you’re going to have to give on Keystone. ... It’s that sort of balancing act,” the aide said.

Still, the GOP aide added that “there’s no poison pill in it at this point” and that the two sides are working diligently to resolve their differences.

The composition of the conference committee has been viewed as a litmus test for whether Boehner can clear a deal through his conservative Conference, with eight of Boehner’s 20 appointed conferees being freshmen. If they can approve the compromise in the conference committee, it’s likely the package could garner enough votes for final passage.

Although House GOP leaders have yet to endorse the idea of linking student loans and the highway bill — which has been discussed privately in the Senate — they remain open to the idea if a deal on both topics can be reached. Some sources have suggested it might be easier to pass both measures together. Reid has floated a proposal to pay for such a deal in a way that has overlapping offsets. But there is a wider consensus on student loans, even though missing the July 1 deadline to keep rates from doubling is less serious than missing the transportation deadline, when some highway projects will stop. Interest rates can be fixed retroactively.

Senate leadership sources were being especially coy Monday and did not want to speak to any of the specifics on either set of talks. In Congress, silence can cut both ways: Either the sides are close to a deal and don’t want to leak the details, or they are far apart and scrambling to find suitable alternatives. Democratic sources, however, indicated that it would be bad for the White House and even their own candidates running for re-election if transportation projects that create jobs lapse and loan rates go up. Though no one is speaking openly about another temporary highway extension, some sources suggested neither party is eager to fall short on the issue.

House GOP leaders are playing a wait-and-see game on student loans. According to GOP leadership aides, Boehner at this point is content to allow Senate Minority Leader Mitch McConnell (R-Ky.) to take the lead in negotiating with Reid. With Republicans in both chambers largely united on the issue — and both leaders wary of a repeat of last winter’s payroll tax cut debacle — it is unlikely McConnell would cut a deal he wasn’t sure would make it through the House.

Republicans in particular are eager to have the issue behind them; Democrats have been relatively successful in painting the party as standing in the way of an extension despite repeated statements to the contrary, and the Democratic Congressional Campaign Committee has used the standoff on student loans to hammer Republicans.

For instance, on Monday the DCCC circulated a release to local media in 60 districts represented by Republicans accusing them of voting “to protect taxpayer subsidies for Big Oil companies instead of stopping these student loan rates from increasing by $1,000 per person at the end of the month.”